The present invention relates to a light source unit which utilizes light emitting diodes and a projector which utilizes the light source unit.
Currently, in many cases, video projectors are used as an image projection unit for projecting an image on a screen of a personal computer, a video image and the like on to a screen.
The projectors of this type utilize many extra-high pressure mercy vapor lamps or metal halide lamps which have high luminance. With these light emitting units, however, there has been an inherent problem caused by their large heat values that a cooling mechanism has to be complex in construction and is made large in size. To cope with this problem, there have been proposed light sources for small projectors which utilize light emitting diodes which have relatively small heat values.
For example, Japanese Unexamined Patent Publication No. 2003-5286 proposes an invention relating to a light source unit for a projector in which a plurality of light emitting diodes are provided in parallel for respective colors so as to produce light sources for red, blue and green light, and these light sources are arranged in such a manner as to face three sides of a dichroic prism, respectively, so that light rays in respective colors are combined together to produce a while light ray.
In the light source unit employing the dichroic prism that has been described above, however, light that has entered in the interior of the dichroic prism is diffused and dispersed to become stray light, and in some cases, the stray light is allowed to leak out. This constitutes a problem that the utilization efficiency of light is decreased.
The invention has been made in view of these situations and an aspect thereof is to provide a light source unit which can enhance the utilization efficiency of the dichroic prism which emits light that is emitted from the plurality of light sources in a direction which is parallel to an optical axis and a projector which employs the light source.